[PATCH] 2.2.14 make_request SMP safe?

[Roger Larsson]

void make_request(int major, int rw, struct buffer_head * bh)
{
	unsigned int sector, count;
	struct request * req;
	int rw_ahead, max_req, max_sectors, max_segments;
	unsigned long flags;

	count = bh->b_size >> 9;
	sector = bh->b_rsector;

	/* Uhhuh.. Nasty dead-lock possible here.. */
	/* return if it could not be locked (already locked!), cheaper and SMP
safe! */
	if (test_and_set_bit(BH_Lock, &bh->b_state)) // if
(!try_lock_buffer(bh))
		return;

The earlier fix was a split test

	if (buffer_locked(bh))
		return;
	/* Maybe the above fixes it, and maybe it doesn't boot. Life is
interesting */

	lock_buffer(bh);

But since interrupts are not disabled (IMHO) and no other locks are held
(IMHO)
there is a small (and rather unlikely) window for a dead-lock...

Or am I mistaken again...

/RogerL
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